1. Field of the Invention
The invention relates to a speech aid system adapted for use by a tracheostomized patient.
2. Description of the Related Art
Vowels of human languages are produced by: generating a glottal sound by vibration of the glottis as a result of air from the respiratory subsystem, and using the tongue, the lips and the soft palate to construct a vocal tract with a shape according to a sound that is to be produced. However, a laryngectomized patient whose larynx is removed and whose windpipe is tracheostomized to be connected to the neck is unable to produce a glottal sound for speech.
U.S. Pat. No. 4,550,427 discloses a conventional artificial larynx having an intraoral speaker for use by a laryngectomized patient. However, volume variation in a spoken sentence is unable to be controlled as desired by the user, so that the voice produced by such a conventional artificial larynx would be somewhat unnatural.